Manufacture of Chlorine
Production of chlorine and sodium/potassium hydroxide via electrolysis of brine with specific electricity consumption thresholds.
Substantial Contribution to Climate Change Mitigation
The specific GHG emissions from chlor-alkali electrolysis must not exceed 0.285 tCO2e per tonne of chlorine, reflecting the EU ETS product benchmark. Since chlorine production is predominantly electricity-driven, the key performance metric is specific electricity consumption, which must be consistent with BAT levels: below 2,790 kWh AC per tonne of chlorine for membrane cells (the only BAT-compliant technology since the mercury cell phase-out deadline of December 2017).
Emissions are calculated covering direct process emissions (primarily from hydrogen co-product handling) and indirect emissions from electricity consumption, verified under the EU ETS Monitoring and Reporting Regulation. The mercury cell process is no longer considered BAT and existing mercury cell plants must have been converted to membrane technology in accordance with the BAT conclusions in the Chlor-Alkali BREF (2014) and the Minamata Convention.
BAT requires optimised membrane cell design with low-resistance membranes, high-performance electrodes (DSA anodes, activated cathodes), and zero-gap or near-zero-gap cell configurations to minimise electrical resistance. Hydrogen co-product must be recovered and used as chemical feedstock or fuel, not vented.
Substantial Contribution to Climate Change Adaptation
A CRVA per Appendix A must cover the electrolysis plant under RCP 4.5 and RCP 8.5 climate projections.
DNSH: Climate Change Adaptation
Physical climate risks must be assessed, including risks from flooding (chlorine is a hazardous gas requiring Seveso-level containment), power supply interruptions from extreme weather, and temperature effects on electrolysis efficiency.
DNSH: Water and Marine Resources
The activity must comply with the Water Framework Directive. Brine purge and process wastewater discharge must meet BAT-AELs from the Chlor-Alkali BREF. Chlorate and bromate levels in discharge must be minimised. Brine must be purified to prevent mercury, if any legacy contamination exists, from entering water bodies.
DNSH: Circular Economy
Spent membranes and electrodes must be recycled where feasible. Brine recycling loops must be maintained to minimise salt consumption. Hydrogen co-product must be fully utilised, not flared.
DNSH: Pollution Prevention and Control
The activity must comply with the Industrial Emissions Directive and Chlor-Alkali BREF. Chlorine emissions to air must not exceed 0.2-0.5 mg/Nm3 at the stack. Asbestos diaphragms are no longer BAT. Mercury emissions (from legacy sites) must not exceed 1 microgram/Nm3. Storage and handling of chlorine must comply with the Seveso III Directive.